Could Meadow Passerine Distribution Within a Grassland System be Influenced by Spatial Variation in the Mowing Schedule

摘要: This study explored meadow passerine capacity to select habitat conditions likely preserve their breeding success. We observed the variation in bird abundance, assessed with point count method, over a 25-year period (1993–2017) within two phytosociological facies of hay-meadows lower Saone Valley (3.000 ha), eastern France: meso-hygrophilic characterized by increasingly early mowing, and hygrophilic mown later, thereby risk nesting failure. At beginning monitoring (1993–2001), birds were evenly distributed facies. Later on, as more than 90% meadows already July 1, became abundant trend was each most species, Whinchat Saxicola rubetra Corn Bunting Emberiza calandra. In areas (55 76 ha) (49 116 territories mapped 2011 territory mapping method invertebrates captured weekly on transects colour plates Barber traps. spite substantially higher invertebrate density sites (6.4 territories/ 10 ha vs. 10.6). Within site however, selected territorial birds. fact, abundance estimated from counts varied negatively percentage 1 200m-radius 2010. apparently adaptive behaviour leading selection later fields seemed be successful since increased until However, after succession extreme climatic events (droughts, late floods), declined thereafter both